---
license: apache-2.0
language:
- en
base_model:
- Qwen/Qwen3.5-4B
pipeline_tag: image-text-to-text
tags:
- agent
- code
metrics:
- code_eval
- accuracy
---
# 🧠 Qwen3.5-4B-AgentCoder

### A Fine-Tuned Model for Enhanced Tool Calling, Code Generation, and Reasoning

- **Author:** Bruno Pistone
- **Repository:** [br1-pist/Qwen3.5-4B-AgentCoder](https://huggingface.co/br1-pist/Qwen3.5-4B-AgentCoder)
- **License:** Apache 2.0
- **Base model:** [Qwen/Qwen3.5-4B](https://huggingface.co/Qwen/Qwen3.5-4B)

---

## Model Description

**Qwen3.5-4B-AgentCoder** is a fine-tuned version of the Qwen/Qwen3.5-4B model, optimized for:
- 🧮 Complex reasoning tasks
- 🧰 Tool calling
- 💻 Code generation

The model was developed through **sequential fine-tuning**, followed by a **Direct Preference Optimization (DPO)** post-training stage to improve alignment, coherence, and reasoning accuracy.

### Highlights
- Post-trained with **DPO** using *chosen/rejected* pairs for better alignment
- Excellent balance between **tool use**, **code generation**, and **reasoning**

---

## 🚀 Direct Use

Qwen3.5-4B-AgentCoder can be used directly for:
- ✅ Tool calling in complex reasoning tasks
- ✅ Code generation for Python, JS, and other languages
- ✅ Multi-domain reasoning (math, logic, Q&A)

### ⚠️ Out-of-Scope Use
- ❌ Highly sensitive or confidential data
- ❌ Domains requiring expert-level specialization
- ❌ Tasks where full explainability is mandatory

---

## 💻 Getting Started

```python
from transformers import AutoModelForCausalLM, AutoTokenizer
import torch
model_name = "br1-pist/Qwen3.5-4B-AgentCoder"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(
model_name,
torch_dtype="auto",
device_map="auto"
)
prompt = "Give me a short introduction to large language models."
messages = [{"role": "user", "content": prompt}]
text = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
model_inputs = tokenizer([text], return_tensors="pt").to(model.device)
generated_ids = model.generate(**model_inputs, max_new_tokens=1024)
output = tokenizer.decode(generated_ids[0], skip_special_tokens=True)
print(output)
```

---

## 🧠 Training Details

### Training Procedure

#### Phase 1 — Post-Training - Direct Preference Optimization (DPO)
After sequential fine-tuning, the model underwent a **DPO** phase to enhance response alignment, reasoning robustness, and factual consistency.

- Learning rate: `3e-6`
- Batch size: `1`
- Gradient accumulation: `4`
- Epochs: `1`
- Beta: 0.1
- Loss type: `sigmoid`
- Warmup steps: `27`
- Sequence length: ~2.5K tokens

##### DPO Data
- ~2.5K chosen/rejected response pairs
- *Rejected* samples synthetically generated to represent poor or incoherent answers
- *Chosen* samples tagged from real conversations

**Objective**
- Encourage the model to prefer *chosen* completions
- Improve clarity, correctness, and helpfulness
- Reduce hallucinations and verbosity

---

## 🖥️ Technical Specifications

### Model Architecture
- Model type: Causal language model  
- Parameters: 4.0B  
- Context length: ~264K tokens  
- Thinking mode: Enabled  

### Compute Infrastructure

**Hardware**
- GPU: NVIDIA H100 (80 GB VRAM)  
- System RAM: 2 TiB  
- Memory per vCPU: 10.67 GiB  

**Software**
- Python: 3.12  
- Transformers: 5.3.0  
- Libraries: `bitsandbytes`, `safetensors`, `torch`, `trl`, `scikit-learn`, `tokenizers`, `psutil`, `py7zr`

---

## 🧾 Citation

**BibTeX**
```bibtex
@article{qwen3.5-4b-thinking-2507-toolcode,
  title={Qwen3.5-4B-AgentCoder: A Fine-Tuned Model for Enhanced Tool Calling, Code Generation, and Reasoning},
  author={Bruno Pistone},
  year={2025},
  journal={Hugging Face Model Hub}
}
```

**APA**
> Bruno Pistone. (2026). *Qwen3.5-4B-AgentCoder: A Fine-Tuned Model for Enhanced Tool Calling, Code Generation, and Reasoning.* Hugging Face Model Hub. https://huggingface.co/br1-pist/Qwen3.5-4B-AgentCoder

---

## 🧭 Recommendations

- Tool use accuracy depends on task complexity  
- Code generation may occasionally produce minor syntax issues  
- Reasoning strongest in structured, logical, and mathematical contexts  
- Avoid using this model for confidential or safety-critical applications  

---

<p align="center">
  <b>🧠 Qwen3.5-4B-AgentCoder — created by Bruno Pistone</b><br>
  <i>Enhanced reasoning, tool calling, and code generation — refined with DPO alignment</i>
</p>